Date of this Version
Efficacy and safety are primary considerations in registration and use of toxicants for vertebrate pest control. Strychnine (0.5%) and zinc phosphide (2%) are currently registered by EPA for prairie dog control, but continued registration is uncertain. Two percent zinc phosphide bait has been suspected of producing lower and more erratic results than strychnine bait. In our study in western Nebraska in fall 1984, indices based on changes in burrow activity showed no difference in efficacy (P=0.66) or variability (P=0.7) of control for strychnine and zinc phosphide, however neither toxicant consistently gave effective control of blackballed prairie dogs. Costs for proper control (prebait and poison) were similar for strychnine and zinc phosphide,, For clean=up of surviving prairie dogs, fumigation with aluminum phosphide was more effective than shooting and more cost effective than shooting combined with fumigation,, Observed non-target wildlife losses (4 horned larks and 2 lagomorphs) were small and of doubtful biological significance. Availability of both strychnine and zinc phosphide is part of the flexibility needed in an integrated approach to prairie dog control. Also, there is need for additional toxicants or methods that will give more consistently efficacious control.